Field of the Invention
The present invention relates to a method and apparatus for investigating an object, and to a method and apparatus for controlling a condition of that object on the basis of the investigation. It is particularly, but not exclusively, concerned with the situation where that object is a culture of microorganisms.
Summary of the Prior Art
Culture systems based on living micro-organisms are widely used for:
(1) systems for the production of useful substances by culturing animal and/or plant cells, micro-organisms or yeast, for applications of those substances in the fields of medicine, diagnosis and foods, PA1 (2) systems of cell activation, e.g. for immunization therapy in the field of medical care, PA1 (3) systems for removing hazardous matter by using micro-organisms, for applications in the field of waste water treatment and (4) systems for farming of fish and shellfish in the field of fisheries.
Research for further improving the practical use of such culture systems is proceeding, and it is desirable to improve the efficiency of all of these systems specifically, for the systems (1) and (4) improvement of productivity is desirable, for system (2) improvement of activation efficiency is desirable; and for system (3) improvement of operation stability is desirable.
In system (1), the amount of useful substances produced by cells is extremely small, for example, a few ng/10.sup.6 to a few .mu.g/10.sup.6 cells per day. Therefore to obtain these useful substances on an industrial basis, improvement of cell concentration in the culture liquid, increase in the capacity of the culture tank and activation of cells (improvement of substance production ability of every cell) are desirable. To improve the cell concentration, by accelerating the multiplication of cells and suppressing death of the cells, it is necessary to collect detailed information about the concentration of the cells. For example, the ratio of the number of living cells (viability) to the total number of cells is desirable, as is the ratio of the number of cells having a potential for division (divisible cell ratio) to the number of living cells. For the activation of the cells, the ratio of the number of cells having a high secretion activity (secreting cell ratio) to the number of living cells is needed.
Conventionally, these ratios were obtained by staining dead cells with a staining agent to distinguish the dead cells from living cells and thereafter a magnified image was observed with a microscope as disclosed in JP-A-2-27977 (1990).
Currently, the majority of activity diagnosis methods which make use of the number of cells as an index are performed by human eyes. However, a few known methods make use of picture image processing and count cultured cells.
JP-A-62-201332 (1987) and JP-A-64-029765 (1989) disclosed a method in which living cells (unstained) and dead cells (stained) were recognized separately by making use of a linear spatial filter. Also, JP-A-2-27977 (1990) referred to above disclosed a method in which living cells and dead cells were discriminated by their sizes by making use of a linear spatial filter without injecting a staining agent into the culture liquid for the micro-organisms. However, both these known methods only obtained viability information. In a system for producing useful substances, information concerning the ratio of secreting cells is particularly important. Also, in system (2) mentioned above, information concerning the ratio of divisible cells, which represents an index indicating the ratio of active cells, is important. However no method of obtaining this information under physiological conditions of cells has been proposed.
In an activated sludge processing system (system (3), it is necessary to prevent the phenomenon of bulking, in which no active sludge is sedimented, in order to obtain stable operation, for the prevention thereof, micro-organism phase appearing in activated sludge groups is an important information and currently the sedimentation of activated sludge is evaluated on the basis of the ratio between aggregative micro-organisms and filamentous microorganisms.
JP-A-61-21786 (1986) disclosed image picking-up with different magnifications when observing microorganisms in sewage water. However no picture image processing was disclosed.
JP-A-61-32182 (1986) disclosed a method in which images of cell specimens are obtained up with different magnifications and the cells were identified based upon the respective picture image information. In the method disclosed, only cells with no multiplication ability such as blood corpuscles, were considered, i.e. this method only considers objects which do not change substantially during the observation period. This document did describe picture image processing of the picture images.
JP-A-64-53157 (1989) disclosed a method in which skin cell samples are observed by a microscope with one magnification. Then, those samples were observed by the microscope with a higher magnification after storing the current position and the characteristics of the cells were measured via picture image processing.